APPROACH 1: Nature and role of the principal liver azoprotein in hepatoazocarcinogenesis: (a) Separation of the principal liver azoprotein into azo dye and protein components. (b) Natures of the azo dye and protein components of the principal azoprotein. (c) Interactions between the principal liver azoprotein and biological macromolecules. AAPROACH 2: Identity and function of the principal target protein of azocarcinogen in normal liver: Effects of azocarcinogen in liver carcinogenesis: (a) The identity and biological activity of the principal target protein of azocarcinogen in normal rat liver. (b) The effects of azocarcinogen on the biological activity of the principal target protein of azocarcinogen during liver carcinogenesis. APPROACH 3: Cell culture studies on the principal liver target protein of azocarcinogen: (a) Establishment of hepatoma cell lines that contain the principal target protein of azocarcinogen of liver. (b) Nature of the activity of the target protein in cultured hepatoma cells.